For TBF Estab. failure, chk the below points::
1)Failure due to Insufficient channel
2)Failure due to MS no response
3)Max PDCH on DSP is not exceeded, confirm for ur GTAC.
4)Check the ports of Abis and DSP boards if it’s mismatch, it’ll also cause to failure.
If all RF condition is correct, u check the above points and let me know.